Evaluation of susceptibility or tolerance of selected major citrus cultivars towards citrus leaf miner, Phyllocnistis citrella stainton (Lepidopters: Gracillaridae) based on innate morphological or physiological attributes in the young expanding citrus leaves were studied in the seedling stage as well as in pre-bearing orchards during spring and winter flushing. Further, focussed on histochemical changes inside the leaf in response to citrus leaf mining morphological parameters like leaf thickness, wax content and trichome density; physiological changes in total phenol content in different leaf ages in the selected cultivars. Citrus maxima Merr was found less susceptible to citrus leaf miner attack among the seven cultivars and had dense trichomes, leaf thickness and higher leaf wax content. Higher the total phenol content, lesser was the pest incidence. Results confirmed that due to leaf mining, injury is caused only to epidermal layer which gets removed/peeled off later exposing the mesophyll tissue. Results confined there is no significant histological changes in the leaves due to mining. Hence, citrus leaf miner could be included under the second category of non-gall forming type.